The present invention, in some embodiments thereof, relates to calibration of measurement processes and devices and, more particularly, but not exclusively, to methods and devices of calibrating units and systems of measuring and/or monitoring electromagnetic interactions with objects.
Various measurement units acquire data by delivering and measuring electromagnetic (EM) signals, such as microwaves and radio waves, for example Network Analyzers, and Time Domain Reflectometers (TDR). Such measurement units deliver EM signals toward a target object and measure RF signals which interact therewith, for example reflected, diffracted, and/or refracted therefrom and/or passing therethrough.
For increasing the robustness and accuracy of such measurement units, it is common to apply, from time to time, calibration processes which compensate for measurement setup inaccuracies. Such a calibration process is usually conducted by measuring the EM signals which are reflected from and/or passed through reference elements with known impedances, for example, Short, Load, Open and/or Through impedance values instead of measuring the EM signals which interact with an actual target object. The known impedances are sometimes referred to as calibration standard elements.
The actual measurements of EM signals which interact with the calibration standard elements are compared to the expected known impedance values so as to derive a correction function or any other measurement manipulation which will correct the actual measurements to the expected values. Most calibration methods are based on the assumption that the measurements of the different calibration standards are conducted under sufficiently similar conditions. Similarly, it is assumed that the actual measurements are conducted in conditions sufficiently similar to the ones existing during the calibration process, for example temperature conditions, cable setup and arrangement and setup components.